Thermal flattener plates



ug 28, 1962 F. w. scHNAcKENBx-:RG 3,051,215

THERMAL FLATTENER PLATES Filed Aug. 2, 1960 2 Sheets-Sheet 1 IN VEN TOR.

F. w. scHNAcKr-:NBERG 3,051,215

Aug. 28, 1962 THERMAL FLATTENER PLATES 2 Sheets-Sheet 2 Filed Aug. 2. 1960 INVENTOR.

Wr wlw y@ mf i Ww United States Patent M 3,051,215 THERMAL FLATIENER PLATES Fred W. Schnackenberg, St. Louis, Mo., assignor to N ordberg Manufacturing Co., a corporation of Wisconsin Filed Aug. 2, 1%0, Ser. No. 47,165 9 Claims. (Cl. 153-32) This invention relates in general to thermal oven flattening plates and more particularly to plates used in flattening rolled sheets of magnesium or the like during heat treatment. It further relates to a method of making thermal oven flattening plates.

Flattening plates are used in the production of sheet magnesium and metals of a similar nature. During heat treatment, to which the sheet metal is subjected after undergoing rolling operations or the like, the attening plates are used to provide a level and smoothly nished ilattening surface for the large sheets.

A continuing problem in the use of such thermal attening plates is that of maintaining a high degree of flatness and a tine iinish during the service life of the plates. The extreme atness is required to insure the atness of the iinished sheets of metal. The finish or smoothness of the surface is important since it, in turn, effects the surface nish of the sheet being heat treated.

A number of factors operate to adversely affect the flatness of the plates and the surface finish. The weight of each plate, for example, is one of its own Worse enemies. It will be understood that these plates, being of substantial size, are normally extremely heavy. In stacking the plates with the magnesium sheets, for example, precedent to heat treatment, they are normally moved by attaching cables from overhead lifts to attachments onthe plates. As the plates are lifted, their extreme weight causes considerable bending stresses to develop. These, of course, are a hazard to plate liatness. The hazard is even more pronounced when the plates are handled after the heat treating cycle is performed. In such case, the plates are still at considerably elevated temperatures and, consequently, bend more easily.

During the heat treating cycle the plates are subjected to extreme temperature ranges such that high thermal stresses are developed. For example, it -is accepted practice to heat treat magnesium sheet for a period up to 24 hours at 900 degrees F. The sheets and consequently the plates are then removed from the furnace While still at a temperature of in the neighborhood of 200 to 50() degrees F. In continuous use, the heating and relativelv rapid cooling cycles tend to cause the plates to warp slightly. In addition, the linish of the plate surfaces is adversely affected to some degree by any bending or warping.

Accordingly, a primary object of this invention is to provide a thermal oven flattening plate which is capable of withstanding substantial thermal stress'while maintaining a prescribed flat surface.

Another object is to provide a flattening plate which is comparatively light in weight and is consequently less subject to bending caused by plate handling operations.

Yet another object is to provide a flattening plate which v has a prescribed fine finish `and maintains this finish throughout the service life of the plate.

Still another Objectis to provide a flattening plate cast of a ferrous alloy such as nodular iron or Meehanite or 3,051,215 Patented Aug. 28,1962

ICC

the like which is of substantially large dimensions yet which has a relatively low weight-to-surface area ratio.

Another object is to provide a flattening plate which permits free circulation of the heat treating atmosphere within its contines.

Yet another object is to provide a flatening plate having lifting lugs which equalize stresses developed during plate handling operations.

Another object is toprovide a flattening plate of 'substantial surface area comprising parallel thinwalls interconnected by generally vertically disposed, transversely extending webbing.

These and other objects of this invention will be found in the following specification and claims wherein like reference numerals identify like parts throughout.

The invention is illustrated more or less diagrammatically in the drawings wherein several embodiments are shown. v

FIGURE l is a view in perspective of a flattening plate embodying this invention,

FIGURE Z is an enlarged partial side elevation of the flattening plate of FIGURE l,

FIGURE 3 is a view taken along line 3 3 of FIG- URE 2,

FIGURE 4 is an enlarged side elevation of a portion of a flattening plate showing another embodiment of this invention, and

FIGURE 5 is an enlarged partial side elevational of still another embodiment of this invention. y

A thermal ilattening plate embodying this invention is indicated generally at 2 in FIGURE l. The plate is comprised of cast metal which might be Meehanite or nodular iron or the like. Grade HD Meehanite, of the type developed by the Meehanite Metal Corporation, Chattanoga, Tennessee, has been found to be ideally suited for these plates; however, other ferrous alloys might be utilized. Plates of various size are used in practice. 'I'hey are all relatively large, however. Dimensions of 4l/2 feet x l13 feet x 61/2 inches are common and the plate'shown might be of these dimensions.

A plate is rst cast inthe general shape seen in FIG- URE 1 with passageways and 4 of similar but inverse cross section extending therethrough. The function of the passageways is somewhat self-explanatory; however, their importance will be emphasized further in the succeeding discussion of the invention. The passageways 3 and 4 are separated by oppositely inclined webs 5 and 6l along the length of the plate. Upper and lower walls 7 and 8 extend the length and width of the plate and provide flat upper and lower surfaces 9 and 10. The walls 7 and 8 are machined after casting to provide these overall ilat surfaces and put a ne nish onthem. It iscommonly-speeied that the surfaces mustnot vary in flatness more than .-005 inch in 13 feet from end to end and have a number micro finish.

' In FIGURES l and 2, the passageways are shown having a iirst configuration with distinctive lifting lugs 12 and 13 disposed on opposed Vwebs 5 and 6; respectively,adja cent opposite ends of the flattening lplate. As will be seen in FIGURE 3, lthe lugs have upperv and lower lips A1li and 15 thereon forreceiving and holding pear-shaped lifting rings of conventional construction. Y

` FIGURE 4 shows a modification of the web construction of the attening plate in which passageways 18: and

. 19 of similar but inverse cross section, are separated by The passageways 25 and 26 are of a configuration generally similar to that shown in the embodiment in FIGURES 1 3. In this embodiment, however, modified passageways 27 having arcuate shaft seats 2S and 29 extending therethrough are provided adjacent the opposite ends of each plate to receive a shaft carrying lifting lugs (notrshown). It has been found that integrally cast lugs are best suited to most operations and provide optimum performance; however, under certain circumstances the lug carrying shafts might be utilized. A unique method is employed in manufacturing these plates such that highly desirable characteristics are imparted to the plates. A'plate is first cast from Meehanite, for example, by conventional methods. Formed therein are series of passageways which extend transversely of the plate from edge to edge. The generally vertical extending webs left between passageways might be of a number of configurations, as is seen in FIGURES 1-4. In such plates lifting lugs are castintegrallywith predetermined webs adjacent opposite ends ofthe plate. In the alternative, passage- Ways of a configuration similar to that shown in FIGURE 5 might be cast. In such case, separate shafts having lift- Y ing lugs at their opposite ends are inserted through special- The webs remaining between the passageways, however, are strategicallyplaced to support the upper and lower walls of the plate and insure the retention of the prescribed atness and nish'throughout the service life placed pasageways.

ly cast passageways of different configuration adjacent opposite ends of the plate. After rough casting, a stress relieving operation is performed on the plate at a temperature in the neighborhood of 1100 degrees F. Of primary importance here is that the annealing temperature be higher, in this case in the neighborhood ofl 200 degrees higher, than any temperatures to which the plate may be subsequently subjected. After the stress relieving operation, the plate is rough machined on its upper and lower surfaces to roughly established predetermined tolerances. Quarterinch rounds are also machined on the edges of the plate itself, the passageways` and the lifting lugs in the case of integrally cast lifting lugs.

' After the rough machining, a second stress relieving operation is performed on the plate at a temperature in the neighborhood of 1100' degrees F., a duplicate of the previous stress relieving operation.

^ VAfter the second stress relieving operation, a fine machiniugoperation is performed on the upperand lower surfaces of the plate to establish the predetermined tolerthe permissible variation in flatness is .005 inch in 13 feet, while a number 125 micro finish-is required.

` The use and operation of this invention isas follows: Plates of this nature are commonlyrused in large heat treating furnaces-to support flattened sheets of magnesium or the like. 'Ihey are stacked with sheets of metal pressed Ybetween theirfopposed surfaces and then subjected to temperatures which might be in the neighborhood of 900 degrees F. for periods of up to 24 hours. i After such time :has elapsed, the platesY and sheets are normally removed to the atmosphere while still at a temperature ranging between 200 and 500 degrees F. rIr'his rapid change of environment, of course, produces high thermal stresses Vthroughout the flattening plate. The plates embodying this invention lare constructed in such a manner that these thermal stressesV do not result in a warping to a degree inconsistent with required tolerances. y Platesvof relatively large size, such as these, would'be of great weight if they were solid. In such case, the bend- 'ing stresses developed during handling operations are ob- Y viously of a very high order. By providing transversely of the plates. The plates thus have the lightness of a substantially hollow structure while retaining the rigidity that a solid plate might have. Consequently, in the lifting and handling operation wherein carrying rings slip over the lifting lugs to alford lifting attachments for an overhead lift, the plates do not bend to a degree exceeding their tolerances.

It will thus be seen that a new and improved thermal attening plate has been shown and described. In addition, a new method of manufacturing thermal flattening plates has been described.

The thermal oven flattening plate which embodies this invention has a relatively low weight-to-surface area ratio which is achieved through the use of properly This construction makes feasible the use of a material such as cast iron or the like, the characteristics of which are h ighly desirable in such a heat treating operation. The plates are machined and annealed according to a prescribed regimen to produce a product which will not vbend or warp outside of prescribed limits and which will maintain a high finish throughout its useful life.'

The foregoing explanation is intended Yto be illustrativev only and not deknitive and the scope of the invention should'ibe limited only by the appended claims.

I claim:

l. A thermal Iflattening plate for rolled metal sheet comprising a plate having a predetermined substantial length and a predetermined lesser Width, said plate having upper and lower surfaces, said plate Vbeing composed of cast metal, a series of laterally disposed passageways in said plate extending therethrough, said pass-ageways separated by a series of transverse walls joining the upper and lower surfaces, a high tolerance finish on each of said surfaces and a'plurality of lifting lugs extending from each of the longitudinal edges of said plate.

2. The attening plate of claim l further characterized l in that said cast metal is cast iron.

.'ances. VIn these plates, as has hereinbefore been set out, j

3. A thermal flattening plate for rolled metal sheet Vcomprising a plate, said plate including relatively thin upper and lower walls having predetermined substantial lengths and predetermined lesser widths, a network of laterally extending webbing connecting said walls and forming a series of laterallyy extending passageways through said plate, saidwalls and webbing being comprised of cast metal and fonned integrally, a high tolerance finish on the outer surface of each-'of said walls and a plurality of lifting lugs extending along the longitudinal edges of said plate and formed integrally with said webbing. j l j 4. Thel flattening plate of claim 3 further characterized in that said webbing comprises a plurality of longitudinally spaced, laterally disposed webs, each of said webs being inclined at an angle to said walls.

5. 'Ihe flattening plate of claim 4 further Vcharacterized in that alternate websfare disposed in oppositely inclined attitudes to corresponding walls. 'Y

. 6. The attening plate of claim 5 further characterized in that said Vlifting lugs com-prise a pair of'lugs on each of saidY longitudinally extending edges, Veach Voneof said lugs being integral with anV oppositely inclined web on the same edge of said plate.

7..A thermal flattening plate for-rolled metal sheet comprising a plate consisting of cast V'Meehanite metal, relatively thin upper and lower Walls having predetermined substantial lengths and predetermined lesser Widths, a network of laterally extending webbing connecting said Walls and forming a series of laterally eX- tending passageways through said plate, said walls and webbing being formed integrally, the surfaces of said walls being at to the extent that they de not vary more than .O05 inch in 13 feet, a high tolerance finish on the outer surfaces of said walls and a plurality of lifting lugs extending along the longitudinal edges of said plate and formed integrally with said webbing.

8. The thermal flattening plate of claim 7 further characterized in that said high tolerance nish is in the neighborhood of a number 125 mie-ro-nish.

9. The thermal flattening plate of claim 7 further 6 characterized in that said plurality of lifting lugs include a pair of lugs on each of said longitudinal edges, said lugs being formed integrally with said webbing, said lugs being positioned to equalize stress throughout the length of said plate when it is lifted.

References Cited in the tile of this patent UNITED STATES PATENTS Great Britain Apr. 20, 1939 

